This invention relates to electrolytic capacitors and specifically to those utilizing an ammonium or amine anthranilate dissolved in a polar organic solvent as electrolyte.
There is commerical need for capacitors which can operate below 0.degree. C. and/or above 100.degree. C., the freezing and boiling points of water, the commonest polar solvent. Thus, electrolytic capacitors today generally use polar organic solvents which have freezing and/or boiling points suitable for the particular capacitor use as well as acceptable conductivities over the range of contemplated use. These properties will, of course, be altered by the nature of the solute. The final electrolyte needs to be stable over the temperature range of operation; not only must it not boil or freeze, but its resistivity should not change significantly over the operating temperature range. It must be capable of anodizing the metal used as anode in order to heal any imperfections or breaks in the dielectric on the anode.
Glycol borate electrolytes are standard in the industry for use above 0.degree. C. However, at temperatures close to 100.degree. C., these electrolytes react via condensation and esterification to give glycol polyborates and water. This reaction limits the use of capacitors containing such electrolytes to maximum temperatures below 100.degree. C. and commonly to about 85.degree. C.
Therefore, for use at about 100.degree. C. or above, other solutes and/or other solvents must be employed. Some of these combinations are not as preferable as others for reasons other than stated above, e.g., manufacturing considerations including such factors as cost, ease of handling, materials interaction leading to sealing problems and leaks, etc.